(a) Any person operating a bicycle shall obey the instructions of official traffic control signals, signs, and other control devices applicable to vehicles, unless otherwise directed by a police officer.
(b) Whenever authorized signs are erected indicating that no right, left or U-turn is permitted, no person operating a bicycle shall disobey the direction of any sign, except where the person dismounts from the bicycle to make any turn, in which event the person shall then obey the regulations applicable to pedestrians.